Faf du Plessis helped South Africa salvage a draw in an epic debut, defying the Australian attack all day Monday to post his maiden Test century.

Du Plessis defended resolutely and shared important partnerships with AB de Villiers (33) and Jacques Kallis (46) before guiding the South African tailenders to 248-8 at stumps in a tense last hour of the second Test at Adelaide.

Du Plessis batted for seven hours and faced 376 balls for his unbeaten 110, sprinkling 14 boundaries into a gritty defensive knock to ensure back-to-back draws between Australia and South Africa in a series for the first time since 1921. The final Test starts in Perth on 30 November.

In the end of the second Test, a late two-wicket burst from Peter Siddle (4-54) removing both Dale Steyn and Rory Kleinveldt for ducks left it up to Morne Morkel (eight not out) to navigate the final over. Australia had plenty of runs on the board having set South Africa an unlikely target of 430 but ran out of time trying to get the last two wickets for victory.

Morkel hit two boundaries in the last over to deprive the injury-depleted Australian attack a victory that most people had expected coming into the final day. "The story just makes it so much better, the fact it was so close," Du Plessis said. "It's hard for a tailender coming in, and you know if you get out you're carrying the weight of a whole nation on your shoulders.

"Morne played it beautifully. He played two straight drives. I went up to him and said, 'Keep playing it straight,' and he said, 'Don't worry, I've got this!"

The 28-year-old Du Plessis, given his test debut here after injured JP Duminy was ruled out of the series last week in Brisbane, made a well-compiled 78 in the first innings and proved his worth to the team with a valiant hundred in the second.

After resuming at 77-4, Du Plessis anchored an 89-run, fifth-wicket stand with De Villiers and 99 for the sixth with Kallis, who was batting with a hamstring injury that has prevented him from bowling or fielding since early on day one.

"Two more wickets would have been lovely," the Australian captain, Michael Clarke, said. "Faf was outstanding. An amazing innings, let alone being on debut, so a lot of credit has to go to him. We go to Perth nil-all. We have to win that Test match."

After having the better of both Tests so far, Australia need a win to have a shot at reclaiming top spot in Test cricket. "I think we can definitely take a lot of confidence where we sit after two Test matches against the No1 team in the world," Clarke said. "I'm confident we'll be in a good place come day one in Perth."